A TV advertisement for a computer game showing a shoot-out between four men was banned yesterday by the advertising watchdog for being too violent.

A voiceover in the commercial for the game Stranglehold said: "Honour is his code. Vengeance is his mission. Violence is his only option."

After an investigation triggered by complaints from the public, the Advertising Standards Authority (ASA) found the advert breached advertising rules relating to violence and cruelty, and health and safety.

The watchdog said the advert for the 18-rated game featured almost continuous shooting and realistic computer-generated scenes of violence.

"We considered the ad was likely to be seen as encouraging and condoning violence," the ASA ruled. "Because the issues raised by the ad could not be addressed with a timing restriction, we considered the only solution was to withdraw the ad from transmission completely."

It considered that the voiceover "suggested that it was honourable to seek revenge and that violence was an acceptable solution to a situation".

One viewer who complained said the advert glorified violence and gun crime and that it was "a dangerous incitement to susceptible people". A second viewer, whose three-year-old son had seen the advert, challenged whether it was acceptable for transmission before 9pm, when young children were likely to see it.

The watchdog said the Stranglehold commercial must not be broadcast again in its current form.

Responding to the ASA investigation, Picture Production Company said it had edited footage of the commercial to show only bullets fired into mid-air, with no one getting shot. It said it believed it was clear to viewers that the footage was animated gameplay, not real-life violence.

The ruling comes amid growing public concern about the proliferation of images in advertisements glamorising knives, guns and sexual violence, reflected in a record number of complaints in 2007 - double the previous year.

The ASA is considering strengthening its procedures amid concerns about the impact of violent imagery on children and teenagers.